Hold-down device for Jacquard-controlled looms

Abstract

A hold-down device for Jacquard controlled loom machines including a resilient element which exerts a spring force on the hook which is attached to the heald of the machine. The hold-down device is arranged between the hook cord and the cord assembly. The spring force provided by the resilient element is determined by the stroke of the Jacquard machine. Where it is desired for the device to be retrofitted to a Jacquard controlled loom machine, a plurality of resilient elements may be arranged in a matrix between two perforated plates, with springs being arranged in guide tubes and a stop member being attached to the cord assembly. The unit formed by the plurality of resilient elements can be arranged at an adjustable height between the frame of the Jacquard machine and the loom.

What is claimed is: 
     
       1. A hold-down device for Jacquard-controlled loom machines, said machine having needles for weaving, in which warp threads are movable in a pattern between two shed positions under control of the Jacquard machine by means of a cord assembly and a pull-down device connected to a frame of the machine, said pull-down device including a spring force exerting means and being further connected at one end to said cord assembly to exert said spring force thereon, comprising: a cord releasably attached to another end of the cord assembly and connected to a respective needle of the Jacquard machine, said cord being pulled downwards against a lifting movement of the needles, and a resilient element arranged releasably between the hook cord and the cord assembly,   wherein the spring force exerting means is constructed to apply said spring force according to predetermined parameters of a weaving process for which the device is used, and said resilient element has a spring force that corresponds to the force required by the Jacquard machine to pull down the needles.   
     
     
       2. A hold-down device according to claim 1, wherein the resilient element comprises a heald carrying a stop and a spring element held between the stop and a fixed part of the frame. 
     
     
       3. A hold-down device according to claim 1, wherein the spring element is a compression spring, in particular a coil spring. 
     
     
       4. A hold-down device according to claim 2, wherein the stop comprises a disc fixed to the heald. 
     
     
       5. A hold-down device according to claim 4, wherein the disc has air passage openings. 
     
     
       6. A hold down device according to claim 2, wherein the heald includes a first and second end and has at said first end a carabiner and at said second end an eye hook by means of which it can be releasably connected to the associated hook cord or cord assembly. 
     
     
       7. A hold-down device according to claim 1, wherein the resilient element is surrounded by a guide tube. 
     
     
       8. A hold-down device according to claim 7, wherein the guide tube has at one of its ends a perforated closure disc with a hole through which a heald can pass, and the spring element acts between a stop carried by said heald and the perforated closure disc. 
     
     
       9. A hold-down device according to claim 7, wherein the guide tube is held at at least one end in a fixed part of the frame and the spring element is fixed at one of its ends between said frame part and the guide tube. 
     
     
       10. A hold-down device according to claim 1, wherein a plurality of resilient elements are arranged as a matrix. 
     
     
       11. A hold-down device according to claim 10, wherein the respective ends of a plurality of guide tubes are held in perforated plates. 
     
     
       12. A hold down device according to claim 11, wherein the perforated plates are connected together and form, together with the resilient elements, a separable unit that can be built into the frame of the machine. 
     
     
       13. A hold-down device according to claim 12, wherein the guide tubes are thin-walled and a perforated support plate is provided that is located between and connected to one of the perforated plates. 
     
     
       14. A hold-down device according to claim 12, wherein the unit provides for predetermined pre-tensioning of the resilient elements by means of space-maintaining pieces.